The instant invention relates to apparatus for printing on a continuous strip, and more particularly to a two-sided printing apparatus which is capable of printing in multiple colors on two sides of a continuous strip, and which is easy to disassemble for maintenance purposes and for replacement of worn parts.
Thermal printing apparatus, and more specifically, two-sided thermal printing apparatus, have heretofore been known in the art. In this regard, U.S. Pat. No. 4,811,036 to Gaskill et al. and application Ser. No. 08/461,392, filed Jun. 5, 1995, entitled TWO-SIDED COLOR PRINTING APPARATUS AND REVERSIBLE PRINT HEAD MOUNTING ASSEMBLY THEREFOR, now U.S. Pat. No. 5,675,369, represent the closest prior art to the subject invention of which the applicant is aware. The '036 patent to Gaskill discloses a printing apparatus operative for applying images to opposite sides of a continuous strip at first and second sequential printing stations. The first printing station is operative for applying a single color image (usually black) to the lower side of the strip, and the second printing station is operative for applying a single color image to the upper side of the strip. The apparatus further includes a feed assembly driven by a stepping motor for advancing the continuous strip from the first printing station to the second printing station and a controller responsive to a predetermined number of stepped rotational increments of the stepping motor for coordinating the printing operations at the first and second printing stations. While the above-described apparatus is effective for applying single color images to each of the opposite surfaces of the strip, the apparatus is not capable of printing multiple-color images on either side of the strip.
The apparatus disclosed in the above-noted application solves many of the aforementioned problems. The apparatus is operable for applying images to opposite first and second sides of a continuous strip, and includes first, second, third and fourth thermal printing assemblies actuatable for applying first, second, third and fourth images to the continuous strip at first, second, third and fourth printing stations, respectively. The first and third thermal printing assemblies are mounted on reversible mounting assembles capable of mounting the respective thermal printing assembly in a first position wherein the printing assembly is actuatable for applying an image to a first side of the strip, and a second position wherein the printing assembly is actuatable for applying an image to a second side of a strip. The apparatus further includes a drive assembly including a rotatable drive roller for longitudinally advancing the strip so that it passes through the printing assemblies, a stepping motor rotatable at a predetermined fixed rate of stepped rotational increments per revolution for rotating the drive roller to advance said strip, and a controller responsive to a predetermined number of stepped rotational increments of the stepping motor corresponding to a predetermined distance between the printing assemblies for actuating the printing assemblies to apply images to the first and second sides of the strip. The stepping motor and controller ensure proper longitudinal alignment of the printed images on the first and second sides of the strip.
While this apparatus is also suitable for its intended purpose, it is somewhat difficult to disassemble for conducting routine maintenance and for replacing worn parts. The present invention is designed for overcoming this limitation of the prior art apparatus.